Simulation of spatially-extended physical processes is already well known and conventionally is implemented on a digital computer which has the ability of modelling the physical process, the complete spatial extent of which is defined by a multiplicity of parameters, utilising signal input/output devices, a logic unit and a memory unit. The memory unit has a first set of memory cells which contain values for the multiplicity of parameters and a second set of memory cells which store a logic unit instruction program. The logic unit is arranged to fetch first instructions from the second set of memory cells and to implement these first instructions on first selected parameter values retrieved from the first set of memory cells in order to compute new values for these parameters which are then returned to the first selected cells of the first set. This procedure is then repeated through second and subsequent instructions implemented on second and subsequent selected parameter values. Intermittently the logic unit recycles through the first, second and subsequent instructions to update the first, second and subsequent parameter values. The development of the physical process is thus simulated on a cyclic basis with each cycle containing a plurality of sequential steps each operating on a selection of parameter values. Each selection is limited by the number of binary bits of information that can be transmitted simultaneously between the logic unit and the memory unit on the conductors interconnecting these units and as a practical matter these conductors are limited in number being substantially fewer than the number of parameters in the multiplicity defining the physical process. Accordingly, the speed of operation of the known simulation method and apparatus is limited and the multiplicity of parameter values cannot be updated simultaneously.